Late last year Adobe screwed up the naming of Lightroom products. Lots of people are confused.
The old computer and folder based Lightroom CC became Lightroom Classic. The old cloud server based Lightroom Mobile became Lightroom CC.
You are reading instructions that apply to Lightroom Classic while trying to make it work in (the new, cloud server based) Lightroom CC.
In the help menu it will say Lightroom Classic Version 7.1.
This is the same problem I'm having.
I cannot compare photos side-by-side or find any option for face recognition.
These seem like very basic tools that are included in most every other photo editing software.
Why not Lightroom CC?
....Why not Lightroom CC?
I don't work the so really don't know.
But, it appears that Lightroom CC (once Lightroom mobile, cloud Lightroom, etc) has an entirely new purpose. It is aimed at providing quality editing to the photographers that use phones, tablets, websites, etc rather than their office computers. It is an "ecosystem" of all the platforms.
Traditional editing feature remain vibrant in both Photoshop and "Classic" (computer, file based) Lightroom.
For photographers that want "side-by-side" or "face recognition" use "Classic".
The real opportunity is to figure out the complex advantages of using the best of both through syncing tools. It is really not about one or the other, but about getting the best of both at once!